Heavy forearm rigging help please: G1 Megatron's cannon arm

[Marthony]

Hello,

I'm designing a G1 comic/cartoon Megatron rig for this fall and am expecting a challenge with the right forearm with the cannon attached. I'll try to keep it light with white PVC pipe and/or cardboard poster tubes, but it could approach 5lbs. I want to rig this for minimum sagging, and maximum control.

The cannon will be permanently attached to the forearm. I accept that I'll have limited use of my right hand with the cannon being so bulky. The forearm will not be connected to any other part of the rig, and will be worn on top of a red long sleeve shirt. The gloves are to be simple black glider gloves so I can use a smartphone. The cannon will also have LED's build into 3 parts of it, and hopefully a speaker.

The leading thought is a forearm & wrist brace, secured with Velcro. The structure & shell of the forearm (double-thickness cardboard) would get attached to that, and again close at the bottom with Velcro. However, the only marketed braces include a wrist component and mean more limited use of my right hand. Second thought is plaster, which I've yet to work with. I don't think sewing velcro into the shirt would work well.

The left forearm will also need to be a matching weight so as to reduce risk of a need to visit a chiropractor; this is why I'm still looking for ideas past the forearm & wrist brace.

How would anyone here approach this please?

Thanks!

 

[OldSkoolEffects]

I've actually been working on just this for some friends, and even being built as low-weight as possible, I don't know if they'll be able to wear it. The big issue is the center of gravity is fairly far from the arm, so it'll want to twist.

 

[Marthony]

What methods have you been looking at?

Thanks for the thought; I'd figured my deltoid muscle will get a good workout from keeping the forearm away from the body, and am planning on changing my gym routine to be as ready as I can for this, but hadn't thought about the twisting effect.

My first thoughts are that the forearm will have to be tightly secured inside the rig, and that perhaps I should cut the long sleeve shirt short and rig it to attach just inside the forearms but not be between me and the forearm rigging.

 

[Marthony]

Ok, I've come up with a new design - I'll connect the forearm & upper arm with an exo-elbow joint:
http://i1276.photobucket.com/albums/y470/Martaxus/Armsystem_zpsf807339d.jpg

Any thoughts on the design? Any ideas as to where best to find these parts? =)

 

[Marthony]

Another version of this design, with the circular joints replaced by triangles & 'loose' bolts yet to be sourced:

http://i1276.photobucket.com/albums/y470/Martaxus/Armsystem2_zpseedddbbb.jpg

Any thoughts on where to get low-profile bolts or similar for the elbow pivot?

 

[Fangoroth]

I feel that, having the forearm rotatable, it won't matter if the rest of the arm is braced or not. It really seems more like what you need is some kind of strapping rig to keep the forearm section attached TO your arm so that it won't twist. What you could do, depending on the durability of the arm itself, is have some strapping over the wrist opening, and grip it to keep it in place and just wear the glove over that. Then, if the resistance on the rotational brackets is high enough, you might be able to keep it in place with a closed fist. Perhaps something with loops for each finger so that your hand determines all of the direction. Maybe not the best idea, but it's what comes to mind.

 

[Marthony]

Interesting thought!

It will take some testing with a mock-up arm to see how much the forearm wants to twist. I was initially thinking of tightly binding the inside of the forearm to my arm, then securing the outer shell of the forearm again over that. There will be bolts running through the bottom of the cannon into the forearm to give it good support, but it is hard to say how much the unit will still want to twist, as a forearm is hardly a rigid rectangle to get a great grip on. I can see how your idea may be needed!

I'm now picturing bolts coming into the forearm from the cannon side, and becoming part of the initial 'wrap' around the forearm, with an additional rigid & flat piece running from just under the bottom of my forearm and exiting the forearm to be graspable by the hand. The outer flap of the forearm would secure over that. The exposed part of the 'stabilizer' could be in the general shape of a large wooden spoon, perhaps with finger notches. It may also be where I build the button to 'fire' the cannon. =)

Thanks Fangoroth!

 

[OldSkoolEffects]

I was also going to do the hand grip thing, but it pretty much means that hand is useless for anything else.

 

[Marthony]

I don't disagree. At best I'll be able to have limited grasping ability...perhaps just enough for holding a drink? =)

I wasn't expecting to be able to do much with this hand given how the cannon will stick out past it, so I'm not too bothered by this. We'll see what improvements can be made to the concept. Perhaps if a glove was rigged to have this built into the back of the hand, the palm of the hand could still be useful...

When and for what kind of event are you hoping to build your version for OldSkoolEffects?

 

[OldSkoolEffects]

It's for a friend to have on display and maybe wear. I'm shooting to make it light enough to wear comfortably by building it like an airframe, but I won't know if it's wearable til it's done.

 

[Marthony]

Interesting. If you call pull that off, then so will I. Let's share our learning and fire fusion cannons together. =)

FYI, I've got a build log going at TransCostumers at Transcostumers -> G1 comic/cartoon Megatron rig; if my details aren't posted to the RPF here, they'll be on that log.

 

[Rnc88]

I encountered a similar issue with a Halo rocket launcher for Halloween a few years ago. I found that including surgical tubing in the arm made holding it more bearable, perhaps if you use a similar technique but by twisting it, it may stay aligned correctly. This could also be painted with latex paint, if left on the exterior to give a sort of an IDW like look.

Looking forward to seeing the final product!

 

[Marthony]

Rnc88, have you any pictures or could you draw some kind of diagram of how you did this? I'm having challenges picturing this.

Thanks!

 

[CB2001]

Having to have built something that was originally meant to be lightweight but turned out to be heavy as all get out (my flamethrower gun and pack), I can say that going with cardboard tubes or paper craft may be the best means to go with. PVC, when you add up a lot of it, even in little pieces, can weigh a lot.

 

[Marthony]

Thanks CB2001. Fortunately I already have a growing collection of poster tubes and should be able to build with mostly cardboard.

 

[Rnc88]

Here is a picture of the basic principal. (pardon the art skills) diagram A is an overview of the completed arm, sans bicep. As this is the right arm, the tubing, the spiral in this case could spin around the arm to counteract the downward force of the cannon. This coupled with expanding foam in the forearm cavity (assuming the is one) could prevent the cannon from spinning, and appearing underslung. Diagram B shows roughly (VERY ROUGHLY) how the tubing could wrap around the arm, as represented by the tube. Finally C shows the basic armature that I used to decrease the strain of carrying an EXTREMELY heavy object (read over 45 lbs). Prongs X, and Y were inserted into the armour, with the joint on the elbow. finally this was covered with a black neoprene strap, so that it could not be distinguished from the left arm. Unfortunately I do not have any pictures, as it was lost in a flood. If the weight is still to much, you could layer the tubing over the shoulder, think like the crisis nano-suit, but with fewer fibres.

 

[Marthony]

Sorry to hear it was lost in a flood Rnc88. I presume it was last year's? I was evacuated in that flood but was lucky regarding losses.

Thanks for the diagram! How did you secure the upper end of the tubing, in a generic Velcro/elastic arm band? How did you connect each end? Was it very constrictive on your arm (blood flow)? How well did it work? Was the direction of the wrapping of tubing important?

Fortunately I don't think my cannon forearm will be too heavy. I'm curious how your body felt with that much weight on one side of your body; did you counter-balance it somehow? In my case I plan to simply weigh down the left forearm once the right side is built, but in a balanced fashion within the forearm so it has no inclination to spin.

 

[Marthony]

Another revision of the elbow joint design...this one should allow for easy adjustments of where the pivot point is. Its down to a matter of finding the 90 degree brackets that will match the turntables plus the t-shaped part with or without a series of holes in them:
http://i1276.photobucket.com/albums/y470/Martaxus/Armsystem4_zps8d8aae60.jpg

 

[CB2001]

Thanks CB2001. Fortunately I already have a growing collection of poster tubes and should be able to build with mostly cardboard.

You're welcome. Like I said, I'm going from personal experience, PVC, especially from pieces, tend to lead to being heavy. However, some materials can be much lighter if used correctly (I found a Backyard FX tutorial on how to make a flamethrower, which I did not use when I was making mine, which aimed to make a flamethrower prop on the cheap and lightweight. Some materials presented may be something to consider.) There's also foam mats (like the kind used for armor builds) that many have used to make some interesting prop replicas.

 

[Rnc88]

Appreciated, but no, it was a minor hurricane in 2012, guess that's what i get for living in the Florida Keys! In all seriousness though, it was attached with an arm band, but the main structure came from the suit itself, due to the rigid nature of fibreglass construction. Overall it was not to constricting, but did take a long time to get used to, and needed the launcher to allow a relaxed stance. The weight wasn't that large of an issue as far as balance, but I would advise against adding weight to the left arm, as all of that mass would be hell on ones back. Carrying the launcher for only a couple of hours practically killed me. (Why throw your life away so recklessly?) In short, the lighter the better.

Concerning the direction, it needs to be wound so that it would make meg's cannon, rotate to the front, so as to ensure the mass of the cannon counteracts this and sits even while idle.

If you can make it light enough, say under about 5 lbs, you will likely be just fine with securing it tightly to the arm. expanding foam can really help here.

good luck, I would love to see how this turns out!